Late Cambrian biogeography: conodont bioprovinces from Korea

Abstract

Although the collisional belt between the North and South China blocks has been well defined in China, the location of its eastward extension in the Korean Peninsula is highly controversial. The Cambro-Ordovician sedimentary rocks in South Korea, the Joseon Supergroup, accumulated in the Ogcheon belt which has been proposed as the suture zone between the North and South China blocks or the block boundary. The Joseon Supergroup comprises five different lithostratigraphic units, and may be divided into two tectonic blocks by the Honam Shear Zone (HSZ) in the Ogcheon belt. Based on the affinities of the Cambrian trilobite faunas, previous studies correlated the Yeongweol unit in the western part of the HSZ with South China and the Duwibong unit in the eastern part of the HSZ with North China. To test the above geodynamic interpretation, this study analyzed and compared the degree of the provinciality of Upper Cambrian conodonts from the Yeongweol and Duwibong units and North and South China. The quantitative test for the Upper Cambrian provincialism shows high bioprovincial affinities between the Yeongweol and Duwibong units and both conodont faunas from the two units display higher bioprovincial affinities with that of North China rather than with that of South China. Their high conodont faunal similarity suggests that the Korean Peninsula might have been included in a larger continental block including the North China and the Korean Peninsula, the Sino-Korean block, in early Paleozoic time. This result is supported by recent studies on lower Paleozoic biogeography, stratigraphy and sedimentology that suggest that the Yeongweol unit of the Joseon Supergroup is more closely correlated with North China than with South China.